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Search: id:A140890
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| A140890 |
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Sum of primes in { 10n-9, 10n-7, 10n-3, 10n-1 }. |
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+0
1
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| 10, 60, 52, 68, 131, 112, 128, 223, 172, 97, 420, 113, 127, 407, 149, 308, 330, 352, 181, 780, 0, 211, 679, 472, 241, 508, 532, 548, 564, 293, 307, 941, 0, 668, 696, 712, 367, 752, 772, 397, 810, 419, 421, 1303, 892, 457, 1391, 479, 487, 990, 1012, 0, 1044, 0
(list; graph; listen)
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OFFSET
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1,1
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FORMULA
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a(n)= (10n-9) isprime (10n-9) + (10n-7) isprime (10n-7) + (10n-3) isprime (10n-3) + (10n-1) isprime (10n-1), where isprime = A010051.- M. F. Hasier, Jun 15 2008
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EXAMPLE
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If n=1, then a(1)=A030430 (-) + A030431 (1) + A030432 (1) + A030433 (-) =0+3+7+0=10
If n=11, then a(11)=A030430 (6) + A030431 (9) + A030432 (7) + A030433 (6)=101+103+107+109=420
If n=21, then a(21)=A030430 (-) + A030431 (-) + A030432 (-) + A030433 (-) =0+0+0+0=0
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MATHEMATICA
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f[n_]:=Plus@@Select[10n-{9, 7, 3, 1}, PrimeQ]; Table[f[n], {n, 60}] (*Chandler*)
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PROGRAM
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(PARI) a(n)=(10*n-9)*isprime(10*n-9) + (10*n-7)*isprime(10*n-7) + (10*n-3)*isprime(10*n-3) + (10*n-1)*isprime(10*n-1) //M. F. Hasier, Jun 15 2008
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CROSSREFS
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Cf. A030430, A030431, A030432, A030433.
Sequence in context: A061001 A055586 A054489 this_sequence A055714 A046762 A066290
Adjacent sequences: A140887 A140888 A140889 this_sequence A140891 A140892 A140893
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KEYWORD
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nonn
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AUTHOR
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Juri-Stepan Gerasimov (2stepan(AT)rambler.ru), Jul 06 2008
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EXTENSIONS
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Corrected and extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), Feb 20 2009
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